Organo-niobium compounds



United States Patent ORGANO-NIOBIUM COB'IPOUNDS John C. Brantley,Bufialo, N.Y., assignor to Union Carbide Corporation, a corporation ofNew York No Drawing. Application August 25, 1955 Serial No. 530,604

7 Claims. (Cl. 260-429) This invention relates to organo-metalliccompounds containing niobium as the metal component and it includescorrelated improvements and discoveries whereby such niobium compoundshaving distinctive properties are obtained.

An object of the invention is to provide organo-metallic compoundscontaining niobium as the metallic component linked to the organiccomponent by carbon to metal bonds.

Other objects of the invention will in part be obvious and will in partappear hereinafter.

The products of this invention have the general empirical formula:

where R is a residue of an organic compound containing a live carbonring, alicyclic in character, which is herein after designated analicyclic cyclopentadienyl carbon ring and has the structure:

X is halogen, n is O, 1 and 2, y is O, 1, 2 and 3 and n+y is 0, 1, 2 and3, the organic residues and atoms of niobium in said compounds being inthe ratio of 2: 1. More particularly, the organic-niobium compounds havethe empirical formulas: R NbX R NbX R Nb(OH) X; R Nb(OH)X R Nb(OH)X; RNbX and R Nb wherein X and R are as defined above, and specifically theempirical formulas: (C H NbCl bis(cyclopentadienyl) niobium trichloride;(C H NbCl bis(cyclopentadienyl) niobium dichloride; (C H Nb(Ol-I) Cl,bis(cyclopentadienyl niobium dihyclroxym onochloride biscyclopentadienyl niobium monohydroxydichloride; (C H Nb (OH) Cl, bis(cyclopentadienyl) monohydroxymonochloride; C H NbCl, bis(cyclopentadienyl) niobium chloride and (C H Nb, bis(cyclopentadienyl)niobium.

Such dihalides and hydroxy dihalides are solid crystalline compoundswhich crystallize in the form of brown and of yellow solids,respectively. They are soluble in benzene and acetone but insoluble indilute hydrochloride acid.

The alicyclic character of the carbon ring is essential for purposes ofthis invention. For example, both cyclopentadiene and indene contain analicyclic cyclopentadienyl ring structure; cyclopentadiene having nodouble bond coordinately shared with an aromatic ring and indene havingonly one double bond of the cyclopentadienyl ring coordinately sharedwith an aromatic ring. In contrast, the five carbon ring in fiuorene,where each of the double bonds in such ring is coordinately shared withan aromatic ring, is not an alicyclic cyclopentadienyl ring structure.

The organo-metallic compounds of this invention may be produced byformation of an alkali metal derivative of an organic compoundcontaining the cyclopentadienyl carbon ring and reaction of theresulting organo-alkali metal compound with a niobium halide asdisclosed and claimed in the co-pending application of Lynch andBrantley, entitled Process for Producing Organo-Metallic Compounds,bearing Serial No. 381,970 and filed September 23, 1953. However, theprocess there disclosed and claimed forms no part of this invention.

According to that process an alkali metal derivative of an organiccompound containing an alicyclic cyclopentadienyl carbon ring may bereacted with niobium pentahalide or niobium oxyhalide to produce thedihalides of this invention. It is to be understood that the termniobium halide as used herein includes oxyhalides as well as halideswhich contain no oxygen. Thus, included within the term are compoundshaving the general formulas: NbX and NbOX where X is halogen and moreparticularly, compounds of the following formulas: NbCl NbBr NbOCl andNbOBr The preferred halogens and halogen components of halides forpurposes of this invention are those which have an atomic number of atleast 17, namely, chlorine, bromine and iodine.

As an illustrative embodiment of a manner in which the invention may bepracticed, the following example is presented, a protective atmosphereof inert gas such as nitrogen or argon being employed where noted.

Example A suspension of cyclopentadienyl sodium was prepared from 19.8g. of finely divided sodium metal and 62.7 ml. of freshly distilledcyclopentadiene in 450 ml. of ethylene glycol dimethyl ether. Thereaction was conducted under an argon atmosphere up to the hydrolysisstage be cause of the high reactivity of the sodium dispersion and thesodium cyclopentadiene compound. 77.9 g. of niobium pentachloride weresuspended in 400 ml. of benzene and this supension cooled to about 0 C.using an ice bath. The cyclopentadienyl sodium solution was addedthereto dropwise with stirring giving a slightly exothermic reaction andforming a brown-colored precipitate as a product. The temperature of thereaction was maintained below 30 C. and stirring was continued for about20 minutes. The reaction mixture which contained bis(cyclopentadienyl)niobium trichloride as well as the dichloride washydrolyzed with ice cold dilute hydrochloric acid. The hydrolyzedmixture was filtered giving a brownish-yellow filter cake which wasdried in vacuo and extracted with benzene. The benzene soluble fractionyielded a brown-yellow solid which was separated into a brown solid anda yellow solid by fractional crystallization from benzene. The brownsolid was determined to be (C H NbCl which is his(cyclopentadienyl)niobium dichoride, and the yelow solid to be (C HNb(OH)Cl which is bis(cyclopentadienyl)niobium monohydroxydichloride.The latter was formed by hydrolysis of his (cyclopentadienyl)niobiumtrichloride.

Taking as illustrative reactants niobium pentachloride and sodiumcyclopentadiene, their reaction with the formation ofbis(cyclopentadienyl)niobium dichloride may be represented by theequation 3 (C H NbCl +3NaCl+organic products Formation of his(cyclopentadienyl)niobium trichloride may be expressed as:

2C H Na+NbCl (C5H5 zNbcla Furthermore, in a manner similar to that abovedescribed, compounds of the type R Nb, wherein R is an organic residueas previously defined, may be prepared utilizing an excessive amount ofsodium cyclopentadiene C H Na which will reduce NbCl to a niobium comwith the C H Na to produce (C H Nb.

V The compounds of this invention may beemployed in catalytic amounts tocatalyze the curing or polymerization of air curing films such as dryingoilsyalkyd resins and curablesilicones. The compounds of this inventionare also, by reasonof their color, their solubility in organic oils andtheir ability to impart colorto solutions and solids in which they aredissolved or with which they are compatible, adapted to serve ascoloring agents,

Having described my invention, what I claim .as new and desire to secure,by Letters Patent is: e

1. An organo-niobium compound having the empirical formula: t e

wherein R is selected from the group consisting cyclopentadienyl andtheindenyl radicals, X represents halogernrt is an integer selected fromthe group consisting of O, l and 2, y is an integer selected from thegroup consisting of 0, 1, 2 and 3 and n+y is an integer selected fromthe group consisting of 2 and 3. 1

2. An organo-niobium halide compound having the empirical formula: 4 55)2 w wherein X represents halogen selected from the group consisting ofchlorine, bromine, andiodine, C l-I repre-f of the sentscyclopentadienyl and w is an integer selected from the group consistingof 2 and 3.

3. An organo-niobium compound having the empirical formula:

wherein X represents halogen selected from the group consisting ofchlorine, bromine, and iodine, and C H represents cyclopentadienyl.

4. Bis(cyclopentadienyl)niobium trichloride.

5. Bis(cyclopentadienyl)niobium dichloride.

6. Bis(cyclopentadienyl)niobium monohydroxydichlon'de.

7. Bis(cyclopentadienyl)niobium dihydroxymonochloride.

References Cited in the file of this patent UNITED STATES PATENTS2,818,416 I Brown et a1 Dec. 31, 1957 2,864,843 De Witt et al. Dec. 16,1958 FOREIGN PATENTS 1,080,357 France May 26, 1954 OTHER REFERENCESWilkinson et al.: J.A.C.S. 76, 4281-4284, Sept. 5,

1. AN ORGANO-NIOBIUM COMPOUND HAVING THE EMPIRICAL FORMULA: